Veneer tape is used in the furniture industry as a process aid in the assembly of composite wood panels having veneered surfaces. Complex versions of these composite wood panels are known as "fancy face" veneered surface panels. The current practice in the furniture industry is to assemble furniture with thin wooden veneers covering a dimensionally stable, but cheaper core board, such as particle board. The decorative wood species desired by consumers, such as oak, maple, cherry, and others, are expensive and thus are most commonly used in the form of thin veneers about 0.8 mm (0.03 in) thick. These veneer pieces are often arranged in a side-by-side relationship and fastened together to form a composite panel or veneer surface.
One method used to fasten the veneers employs a non-pressure sensitive adhesive tape having a water-activated gum adhesive on a kraft paper backing. A worker pulls the gum side of the tape across a wetted sponge where it picks up enough moisture to become tacky. The worker then applies the tape to one of the veneers to be joined, and uses the free end of the tape to pull that piece into edge contact with a second piece. The tape is then rubbed down onto the second piece, and the process is repeated until the full surface is completed. As the gum of the tape loses water it becomes non-tacky, and forms a secure, permanent bond with the wood and the other layers of tape.
Many small pieces of tape may be required to hold the pieces of surface veneer in place on a normally sized piece of furniture. Consequently there may be spots where multiple layers of tape exist. Five to seven tape layers are common for some fancy faces. This is particularly the case where the joined veneers are small, the design is intricate, and mitered corners are made.
After the pattern is assembled it is joined to the core board. The core board is run through a roll coater that applies glue to the surface of the board. The taped veneer assembly is positioned on the glued board and then pressed to the board. If a cold press is used, the glue is commonly a water-based vinyl glue. For a hot press, the glue is urea based. Cold press conditions are typically 4.2 kg/cm.sup.2 (60 psi) for 45 minutes. Hot press conditions vary by manufacturer, but may reach temperatures of up to 149.degree. C. (300.degree. F.) or higher and pressures of up to 8.8 Kg/cm.sup.2 (125 psi) for 1-7 minutes.
After coming out of the press the parts are sanded to remove the tape. Because the tape has formed a permanent bond to the wood, it must be sanded off of the veneer surface. Aggressive cross-grain sanding removes most of the tape. After cross-grain sanding, the parts typically go through three more sanding steps to prepare the surface for staining and varnishing.
A strongly negative aspect of cross-grain sanding is that the veneer is also aggressively sanded, and frequently has deep scratches that can be removed only by further sanding. Also, frequently the veneer is sanded through, exposing the core board underneath. A sanded-through part cannot be repaired, and is thrown away.
Because the kraft paper backed tape is opaque, when a joint is misaligned, it may not be discovered until the tape is sanded off. Also, if a seam opens up before the pressing operation, creating a gap between two pieces of veneer, it may not be detected before the glue has set.
Waste also occurs when the tape or glue is not totally removed during sanding, resulting in differences and non-uniformities in stain absorption and appearance. Additional losses occur when veneers are sanded too thinly so as not to accept stain adequately. Also if the laminating glue is too near the surface of the veneer, stain will not take to the surface as readily and uniformly as it takes to surfaces in which the veneer is thicker.
Waste associated with the process in which veneers are taped together with a water-activated paper tape are estimated at up to 50% depending upon the intricacy of the veneer pattern. Veneers are currently valued at up to 30 dollars per square foot depending upon the type of wood and the grain pattern. Wasting up to half of this product amounts to significant losses.
There is also an economically driven trend toward thinner veneers, such as 0.5 mm (0.02 in) or less. As veneers become thinner, however, the margin for sanding becomes tighter, and furniture makers can less afford to sand down those veneer skins. A non-damaging removal of veneer tape would greatly reduce the scrap rate, and allow furniture makers to use thinner, and less expensive, wood veneers.